drivers/hwmon/lm75.c

   1 /*
   2     lm75.c - Part of lm_sensors, Linux kernel modules for hardware
   3              monitoring
   4     Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/slab.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/i2c.h>
  26 #include <linux/hwmon.h>
  27 #include <linux/hwmon-sysfs.h>
  28 #include <linux/err.h>
  29 #include <linux/mutex.h>
  30 #include "lm75.h"
  31
  32
  33 /* Addresses to scan */
  34 static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  35                                         0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  36
  37 /* Insmod parameters */
  38 I2C_CLIENT_INSMOD_1(lm75);
  39
  40 /* Many LM75 constants specified below */
  41
  42 /* The LM75 registers */
  43 #define LM75_REG_CONF           0x01
  44 static const u8 LM75_REG_TEMP[3] = {
  45         0x00,           /* input */
  46         0x03,           /* max */
  47         0x02,           /* hyst */
  48 };
  49
  50 /* Each client has this additional data */
  51 struct lm75_data {
  52         struct i2c_client       client;
  53         struct class_device *class_dev;
  54         struct mutex            update_lock;
  55         char                    valid;          /* !=0 if following fields are valid */
  56         unsigned long           last_updated;   /* In jiffies */
  57         u16                     temp[3];        /* Register values,
  58                                                    0 = input
  59                                                    1 = max
  60                                                    2 = hyst */
  61 };
  62
  63 static int lm75_attach_adapter(struct i2c_adapter *adapter);
  64 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
  65 static void lm75_init_client(struct i2c_client *client);
  66 static int lm75_detach_client(struct i2c_client *client);
  67 static int lm75_read_value(struct i2c_client *client, u8 reg);
  68 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
  69 static struct lm75_data *lm75_update_device(struct device *dev);
  70
  71
  72 /* This is the driver that will be inserted */
  73 static struct i2c_driver lm75_driver = {
  74         .driver = {
  75                 .name   = "lm75",
  76         },
  77         .id             = I2C_DRIVERID_LM75,
  78         .attach_adapter = lm75_attach_adapter,
  79         .detach_client  = lm75_detach_client,
  80 };
  81
  82 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
  83                          char *buf)
  84 {
  85         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  86         struct lm75_data *data = lm75_update_device(dev);
  87         return sprintf(buf, "%d\n",
  88                        LM75_TEMP_FROM_REG(data->temp[attr->index]));
  89 }
  90
  91 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
  92                         const char *buf, size_t count)
  93 {
  94         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  95         struct i2c_client *client = to_i2c_client(dev);
  96         struct lm75_data *data = i2c_get_clientdata(client);
  97         int nr = attr->index;
  98         unsigned long temp = simple_strtoul(buf, NULL, 10);
  99
 100         mutex_lock(&data->update_lock);
 101         data->temp[nr] = LM75_TEMP_TO_REG(temp);
 102         lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
 103         mutex_unlock(&data->update_lock);
 104         return count;
 105 }
 106
 107 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
 108                         show_temp, set_temp, 1);
 109 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
 110                         show_temp, set_temp, 2);
 111 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
 112
 113 static int lm75_attach_adapter(struct i2c_adapter *adapter)
 114 {
 115         if (!(adapter->class & I2C_CLASS_HWMON))
 116                 return 0;
 117         return i2c_probe(adapter, &addr_data, lm75_detect);
 118 }
 119
 120 static struct attribute *lm75_attributes[] = {
 121         &sensor_dev_attr_temp1_input.dev_attr.attr,
 122         &sensor_dev_attr_temp1_max.dev_attr.attr,
 123         &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
 124
 125         NULL
 126 };
 127
 128 static const struct attribute_group lm75_group = {
 129         .attrs = lm75_attributes,
 130 };
 131
 132 /* This function is called by i2c_probe */
 133 static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
 134 {
 135         int i;
 136         struct i2c_client *new_client;
 137         struct lm75_data *data;
 138         int err = 0;
 139         const char *name = "";
 140
 141         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 142                                      I2C_FUNC_SMBUS_WORD_DATA))
 143                 goto exit;
 144
 145         /* OK. For now, we presume we have a valid client. We now create the
 146            client structure, even though we cannot fill it completely yet.
 147            But it allows us to access lm75_{read,write}_value. */
 148         if (!(data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
 149                 err = -ENOMEM;
 150                 goto exit;
 151         }
 152
 153         new_client = &data->client;
 154         i2c_set_clientdata(new_client, data);
 155         new_client->addr = address;
 156         new_client->adapter = adapter;
 157         new_client->driver = &lm75_driver;
 158         new_client->flags = 0;
 159
 160         /* Now, we do the remaining detection. There is no identification-
 161            dedicated register so we have to rely on several tricks:
 162            unused bits, registers cycling over 8-address boundaries,
 163            addresses 0x04-0x07 returning the last read value.
 164            The cycling+unused addresses combination is not tested,
 165            since it would significantly slow the detection down and would
 166            hardly add any value. */
 167         if (kind < 0) {
 168                 int cur, conf, hyst, os;
 169
 170                 /* Unused addresses */
 171                 cur = i2c_smbus_read_word_data(new_client, 0);
 172                 conf = i2c_smbus_read_byte_data(new_client, 1);
 173                 hyst = i2c_smbus_read_word_data(new_client, 2);
 174                 if (i2c_smbus_read_word_data(new_client, 4) != hyst
 175                  || i2c_smbus_read_word_data(new_client, 5) != hyst
 176                  || i2c_smbus_read_word_data(new_client, 6) != hyst
 177                  || i2c_smbus_read_word_data(new_client, 7) != hyst)
 178                         goto exit_free;
 179                 os = i2c_smbus_read_word_data(new_client, 3);
 180                 if (i2c_smbus_read_word_data(new_client, 4) != os
 181                  || i2c_smbus_read_word_data(new_client, 5) != os
 182                  || i2c_smbus_read_word_data(new_client, 6) != os
 183                  || i2c_smbus_read_word_data(new_client, 7) != os)
 184                         goto exit_free;
 185
 186                 /* Unused bits */
 187                 if (conf & 0xe0)
 188                         goto exit_free;
 189
 190                 /* Addresses cycling */
 191                 for (i = 8; i < 0xff; i += 8)
 192                         if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
 193                          || i2c_smbus_read_word_data(new_client, i + 2) != hyst
 194                          || i2c_smbus_read_word_data(new_client, i + 3) != os)
 195                                 goto exit_free;
 196         }
 197
 198         /* Determine the chip type - only one kind supported! */
 199         if (kind <= 0)
 200                 kind = lm75;
 201
 202         if (kind == lm75) {
 203                 name = "lm75";
 204         }
 205
 206         /* Fill in the remaining client fields and put it into the global list */
 207         strlcpy(new_client->name, name, I2C_NAME_SIZE);
 208         data->valid = 0;
 209         mutex_init(&data->update_lock);
 210
 211         /* Tell the I2C layer a new client has arrived */
 212         if ((err = i2c_attach_client(new_client)))
 213                 goto exit_free;
 214
 215         /* Initialize the LM75 chip */
 216         lm75_init_client(new_client);
 217
 218         /* Register sysfs hooks */
 219         if ((err = sysfs_create_group(&new_client->dev.kobj, &lm75_group)))
 220                 goto exit_detach;
 221
 222         data->class_dev = hwmon_device_register(&new_client->dev);
 223         if (IS_ERR(data->class_dev)) {
 224                 err = PTR_ERR(data->class_dev);
 225                 goto exit_remove;
 226         }
 227
 228         return 0;
 229
 230 exit_remove:
 231         sysfs_remove_group(&new_client->dev.kobj, &lm75_group);
 232 exit_detach:
 233         i2c_detach_client(new_client);
 234 exit_free:
 235         kfree(data);
 236 exit:
 237         return err;
 238 }
 239
 240 static int lm75_detach_client(struct i2c_client *client)
 241 {
 242         struct lm75_data *data = i2c_get_clientdata(client);
 243         hwmon_device_unregister(data->class_dev);
 244         sysfs_remove_group(&client->dev.kobj, &lm75_group);
 245         i2c_detach_client(client);
 246         kfree(data);
 247         return 0;
 248 }
 249
 250 /* All registers are word-sized, except for the configuration register.
 251    LM75 uses a high-byte first convention, which is exactly opposite to
 252    the usual practice. */
 253 static int lm75_read_value(struct i2c_client *client, u8 reg)
 254 {
 255         if (reg == LM75_REG_CONF)
 256                 return i2c_smbus_read_byte_data(client, reg);
 257         else
 258                 return swab16(i2c_smbus_read_word_data(client, reg));
 259 }
 260
 261 /* All registers are word-sized, except for the configuration register.
 262    LM75 uses a high-byte first convention, which is exactly opposite to
 263    the usual practice. */
 264 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
 265 {
 266         if (reg == LM75_REG_CONF)
 267                 return i2c_smbus_write_byte_data(client, reg, value);
 268         else
 269                 return i2c_smbus_write_word_data(client, reg, swab16(value));
 270 }
 271
 272 static void lm75_init_client(struct i2c_client *client)
 273 {
 274         int reg;
 275
 276         /* Enable if in shutdown mode */
 277         reg = lm75_read_value(client, LM75_REG_CONF);
 278         if (reg >= 0 && (reg & 0x01))
 279                 lm75_write_value(client, LM75_REG_CONF, reg & 0xfe);
 280 }
 281
 282 static struct lm75_data *lm75_update_device(struct device *dev)
 283 {
 284         struct i2c_client *client = to_i2c_client(dev);
 285         struct lm75_data *data = i2c_get_clientdata(client);
 286
 287         mutex_lock(&data->update_lock);
 288
 289         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 290             || !data->valid) {
 291                 int i;
 292                 dev_dbg(&client->dev, "Starting lm75 update\n");
 293
 294                 for (i = 0; i < ARRAY_SIZE(data->temp); i++)
 295                         data->temp[i] = lm75_read_value(client,
 296                                                         LM75_REG_TEMP[i]);
 297                 data->last_updated = jiffies;
 298                 data->valid = 1;
 299         }
 300
 301         mutex_unlock(&data->update_lock);
 302
 303         return data;
 304 }
 305
 306 static int __init sensors_lm75_init(void)
 307 {
 308         return i2c_add_driver(&lm75_driver);
 309 }
 310
 311 static void __exit sensors_lm75_exit(void)
 312 {
 313         i2c_del_driver(&lm75_driver);
 314 }
 315
 316 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
 317 MODULE_DESCRIPTION("LM75 driver");
 318 MODULE_LICENSE("GPL");
 319
 320 module_init(sensors_lm75_init);
 321 module_exit(sensors_lm75_exit);